The invention relates to a device for holding and feeding a printing plate to a plate cylinder of a printing machine.
In printing machines, it has become known heretofore to provide a magazine for holding ready and changing a printing plate of a plate cylinder. The published European Patent Document EP 0 654 349 A1 discloses a device of the foregoing general type for holding and feeding a printing plate to a printing cylinder of a printing machine. The device described in this European patent document is provided with a holding device having a holding element and having a supporting surface, it being possible for a printing plate to be placed with one edge on the supporting surface and held by the holding element in a predefinable alignment on a side surface of the printing plate. In this way, a printing plate can be kept ready for a quick change in a printing machine.
The holding device is arranged parallel to the plate cylinder and constructed so that it is movable in vertical direction. The holding device can be moved from a lower rest position into an upper feeding position. Also provided is a guide element, which has at least one guide surface, the guide element being movably mounted and having the ability to be moved from a rest position into a feeding position. In the feeding position, the guide surface defines a feeding direction for feeding the printing plate to the plate cylinder. The guide element is mounted so as to be rotatable about an axis of rotation and is connected to a pneumatic cylinder via a mounting. If the holding device is moved upwardly into the feeding position, the pneumatic cylinder then pivots the guide surface in the predefined feeding direction, so that a printing plate placed on the supporting surface can be pushed along the guide surface into a holding device belonging to the plate cylinder.
The heretoforeknown device is relatively complicated, as the result of the use of a pneumatic cylinder, and is expensive to produce.
It is accordingly an object of the invention to provide a simplified and cost-effective device for holding and feeding a printing plate to a plate cylinder of a printing machine.
With the foregoing and other objects of the invention, there is provided, in accordance with the invention, a device for holding and feeding a printing plate to a plate cylinder of a printing machine, comprising a holding device and a member having a supporting surface, the printing plate being placeable or disposable by one edge thereof on the supporting surface and being holdable in a predefinable alignment by the holding device, a mounting for movably supporting the holding device on the printing machine so that the holding device is movable from a rest position into a feeding position, a guide element having at least one guide surface, the guide element being movably mounted on the holding device and being movable from a rest position into a feeding position, the guide surface, in the feeding position, defining a feeding direction for feeding a printing plate to the plate cylinder, and a lever device via which the guide element is operatively connected to the printing machine, the guide element being movable automatically from the rest position into the feeding position by movement of the holding device.
In accordance with another feature of the invention, the guide element has two guide surfaces defining a holding space for a printing plate therebetween, the guide element having an axis of rotation disposed at least approximately parallel to an axis of rotation of the plate cylinder, the guide element being rotatable so that an end region of a respective printing plate disposed in the holding space is bent in the feeding direction.
In accordance with a further feature of the invention, the lever device is a roller with a lever arm, the roller being operatively connected to the guide element via the lever arm, the roller being rollable on a rolling surface from the rest position into an operating position during the movement of the holding device, the rolling surface being formed so that the guide element is movable by the roller into the feeding position, via the lever arm, as the roller rolls from the rest position into the operating position.
In accordance with an added feature of the invention, the rolling surface is an inclined plane with a defined angle of inclination.
In accordance with an alternative feature of the invention, the lever device is constructed as a driver arm and a triggering pin, the driver arm being mounted so as to rotate about an axis of rotation on the holding device, and the triggering pin being formed on the printing machine, the driver arm being operatively connected to the guide element, and the driver arm and the triggering pin being arranged so that, during the movement of the holding device from the rest position into the feeding position, the driver arm is rotated by the triggering pin into the feeding position, the guide element being also rotated into the feeding position, and the driver arm being rotated into the rest position by the triggering pin during the movement of the holding device from the feeding position into the rest position, the guide element also being rotated into the rest position.
In accordance with an additional feature of the invention, the supporting surface is formed in a rotatably mounted holding bracket, and there is included a stop element formed on the guide element, the holding bracket being biased against the stop element, the stop element, in the rest position of the guide element, holding the holding bracket in an operating position wherein the supporting surface blocks the feeding direction, and in the feeding position of the guide element, the stop element releasing the holding bracket, and the holding bracket being moved into an operating position, wherein the supporting surface clears the feeding direction.
In accordance with yet another feature of the invention, the supporting surface has an edge elevatable in the direction of the holding space, the edge, during a transition of the holding bracket from the rest position into the operating position, being bringable into contact with a printing plate disposed on the supporting surface, so that the printing plate remains standing on the supporting surface and is not released.
In accordance with yet a further feature of the invention, the guide surface is an inner guide surface having an upper region inclined in a direction of a second guide surface up to a bending edge.
In accordance with yet an added feature of the invention, the bending edge is formed as a rotatably mounted roller.
In accordance with a concomitant feature of the invention, the guide surface is an outer guide surface formed by rotatably mounted rollers arranged in one plane.
An advantage of the invention is that the guide element is operatively connected to the printing machine via a lever device, so that the guide element is automatically rotated from the rest position into the feeding position by the movement of the holding device. In this way, the use of a pneumatic cylinder is avoided, so that the holding and feeding device according to the invention is less expensive to produce, and no additional control for a pneumatic cylinder is needed.
The guide element preferably has two guide surfaces, a holding space for a printing plate being defined between the guide surfaces. In addition, the guide element is mounted so that it can be rotated about an axis of rotation, the axis of rotation being arranged at least approximately parallel to the alignment of the guide surfaces. The mounting for the guide element is preferably constructed so that an end region of a printing plate, which is arranged in the holding space, is bent over the first and the second guide surface in the predefined feeding direction.
A result thereof is that only the end region of the printing plate is bent in the predefined feeding direction, so that the remaining part of the printing plate is held in the predefined holding position. A compact and narrow construction of the guide element is therefore possible, so that the guide element has a low mass and, therefore, is easy to operate.
A preferred embodiment of the lever device calls for the use of a roller which rolls over a rolling surface, the rolling surface being formed in such a manner that the roller, as it rolls, moves the guide element from the rest position into the feeding position via a lever. The use of a roller with a rolling surface is a simple and cost-effective principle in order to execute a rotation of the guide element as a function of the movement of the holding element.
In a preferred embodiment, the rolling surface is formed by an inclined plane with a defined angle of inclination to the direction of motion of the holding device.
A further embodiment of the lever device calls for a lever arm which interacts with a triggering pin. The triggering pin is arranged on the frame of the printing machine. The lever arm is rotatably mounted on the holding device and is operatively connected to the guide element. During the movement of the holding device from the rest position into the feeding position, the lever arm is moved past the triggering pin and rotated by the triggering pin into an operating position. As a result of the rotation of the lever arm into the operating position, the guide element is simultaneously rotated from the rest position into the feeding position via the operative connection. If the holding device is moved back again into the rest position from the feeding position, then the lever arm is again rotated into the rest position by the triggering pin, the guide element also being rotated back into the rest position from the feeding position. The use of a rotatably mounted lever arm interacting with a triggering pin constitutes a simple principle with which an adequate torque is provided to rotate the guide element into the feeding position and back into the rest position.
In a preferred embodiment, the supporting surface is formed by a holding bracket, which is biased against a stop so that the supporting surface is urged to clear the feeding direction. In addition, the holding bracket is mounted on the holding device, so that during rotation of the guide element from the rest position into the feeding position, the stop element is rotated away by the holding bracket, and the supporting surface clears the feeding direction.
In a special embodiment, an edge elevated in the direction of the holding space is formed on the supporting surface and, during the transition of the holding bracket from the rest position into the operating position, is bringable into contact with a printing plate standing on the supporting surface, so that the supporting surface does not clear the feeding direction during the movement of the holding device into the feeding position. only by lifting the printing plate over the edge outwardly does the movement of the supporting surface completely out of the feeding direction result because of the bias on the holding bracket, and the printing plate is able to be pushed in the predefined feeding direction into a holding device belonging to the printing cylinder.
In a preferred embodiment, the guide surface, which is arranged between the holding space and the printing machine, has a defined bending edge, with which a printing plate inserted into the holding space is bent at a defined, fixed bending line as the guide element is pivoted into the feeding position. In an advantageous embodiment, the bending edge is formed by a rotatably mounted roller, which reduces the friction occurring as the printing plate is inserted between the printing plate and the inner guide surface in the direction of the plate cylinder.
In a further preferred embodiment, the outer guide surface, which is arranged opposite the inner guide surface, is formed by one or preferably several rotatably mounted rollers. The rollers are preferably aligned perpendicularly to the feeding direction of the printing plate.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a device for holding and feeding a printing plate to a plate cylinder of a printing machine, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings, which: